Zirconium opacifier and method of making same



Patented Jan. 20, 1931 UNITED STATES, PATEN'T OFFICE CHARLES J. xINzIE, OF NIAGARA FALLS, Nnw ronx, AssreNon TO THE TITANIUM ALLOY MANUFACTURING COMPANY, on NEW YORK, N. .Y., A CORPORATION on ZIRGONIUM OPAGIFIER AND METHOD or MAKING SAME No Drawing.

' improved methods of producing enamels and glazing glasses in which zirconium is used as an opac fier, and such product 1s introduced into the ingredients of the enamel mix for producing the frit subsequently employed for the coating inthe finally vitrified enamel products.

The objects of my invention are, among other things, to produce a new and improved opacifier comprising zirconium in which the opacity contributed by the zirconium may be better controlled and utilized than by previous methods now known. Heretofore in producing enamel glasses the zirconium compounds in the form of zirconium oxide, zircon or zirconium silicate and various double zirconium silicates, have been incorporated in the batch and smelted in the usual wag to produce fluid enamels.

roadly speaking, I have discovered a new zirconium product and methods of making same in which sodium zirconium silicate is used to produce opacity in vitreous enameling glasses, more particularly those enamels which when smelted Will be sufiiciently fluid to pour at temperatures below 1100? C. I have also discovered that such sodium zirconium silicate will produce far greater opacity than with the use of unaltered zirconium silicate at the temperatures mentioned. My experiments have shown that sodium zirconium silicate when incorporated into a suitable enamel batch composition and smelted at a temperature around 1080 C. yielded a glass which when prepared to slip for enameled ware produced enamels vastly more opaque than did the same enamel composition containing zlrconlum slllcate.

' v The diflerence in opacity between the two enamel coatings of equal weight per unit area was such thata much smaller quantity of the enamel slip made from the glass containing the zirconium introduced as sodium zirconium silicate was required to produce enamels of equal opacity. Eor example, in-

stead of applying say 50 grams of enamel 'er square foot of surface to produce suitale enameled ware when uslng a slip con- Zirconium silicate is Application filed September 7, 1928. Serial No. 304,619.

taining glass made from zirconium silicate, enameled ware of equivalent opacity and whiteness may be prepared by applying, less than 35 grams of enamel made from glass containing sodium zirconium silicate. Such are largely,'if not wholly, lost, and that no 2 practical advantages by way of opacity and coloring elfects are derived from using sodium zirconium silicate as compared with zirconium silicate at such high temperatures. According to my invention, I have'ascertained from prolonged experimentation that for enamels which can be smelted at temperatures below 1100 C., .or for enamels fluid enough to pour at temperatures below 1100 0., sodium zirconium silicate produces a more intense opacity than does zirconium silicate. Such novel product may be prepared in the following preferred manner: p 7 wet milled to a degree of finenessrepresented by all passing a 325 mesh standard testing sieve. The zirconium silicate is then dried to essentially complete expulsion of contained water.

i The dried zirconium silicate mass is then broken up roughly and mixed with soda ash (sodium carbonate) in the following propormesh sieve.

78 parts by weight I The charge during all stages. of reactionis I 'as' follows apparently completely dry (not sin'ter'ed),

and as finishedthe product is only slightly aggregated and needs only a mild degree of disintegration to 'putin form for packing and use. I

The temperatures. specified, produce -aprocluct of good color tone. Higher temperaturesresult in development of yellowish to greyish tones which are undesirable .mainly on account of thetone. beingnot pleasing to the eye. There has been foiuid no detrimental effect upon the color of'resultant enamel glass or finished enamel, due. to use of such overheated and discoloredproducts. I-prefer to use the. temperature-which gives-afair- 1y. rapid reactionandlightest tone to; product avoidinghigher temperatures than are necessary to accomplishment ofthese. ends.

- Having found thatthenormal sodium zirconium silicate produced byroasting a mixture of milled zirconium silicate. and sodaash at temperatures of about 900+950 (1, 1

found also that thisproduct when'dry disintegrated and stored for use in packages other than air tight containers, had a tendency to cake or harden so that subsequent. disintegration was necessary before same could be used. in enamel batches. Such hardening was a decided defect as. regards thesuccessful use. of such product. .I discovered that such caking or hardening was always. ac-

companied by absorption of moistureand that when the product had absorbedabout 2% of moisture no further caking followed. Hence if-the freshly roasted mass (sodium zirconium silicate) waskept in a. state. ofslow agitation while air charged with moisture was passed through. or over the. mass inmotion until about-2% of moisturewasabsorbed, no tendency. to cake developed in the product when packed bags or barrels. and this opacifier remained permanently soft; also if such roasted mass was extracted with water and driedthe resulting product could be disintegrated and the powdered opacifie-r stored permanently without any undesirable caking. 1 However I preferred not to resort to either of these expedients, and I further discovered that. a satisfactory noncaking zirconium opacifier could be made according to. the. methods hereinbefore described where less than the theoretical quantity of soda ash (sodium carbonate) required to form a normal sodium zirconium silicate was employed for the charge to be roasted, which leaves a part of the zirconium silicate undecomposed.

As azresu-lt. of my experiments Ihave discoveredthatan.improvedrzirc-onium opacifier hav ng the following composition was as c ve in P d ng opac y i namel Wli'l'ClT can be smelt ed and pourcdat tempera -tures'be'lo w 11 00-"C'.,"as the normalsoclium zirconium silicate, and furthermore such new productdid not harden or cake upon storage.

My new product was .chemically analyzed.

Zirconium oxide (ZrO 54l78-% Silica (SiO- "28.22% Sodium oxide (Na O) H. 17 'litanicoxideiTiOQ 0.12%- Iron oxide (Fe O 0.08% Aluminumoxide (A1 0 1.11% Phosphoric anhydride (P 9 0.59 Carbon dioxide (CO 0.44% Moisture QH O) 10.49%

The aluminum oxide, phosphoric anhydride, iron and titanium oxides are incidental impurities, while the carbon, dioxide represents. that contained in thesmallamount of uncombined sodium carbonate.

In addition to the non-caking: advantages hereinbefore described, :such, product. hasthefurther advantage over the normal s odium. zirconium silicatev in building. lip/the enamel. batch, since moreofthe required boric an; hydride (B 0 ,may besuppliedasborax (Na B O- than was possible with. thenormal sodium zirconium silicate. because. of the lower sodium content.

In enamel mix formulae. using my improved zirconium -op-acifier all or substantially all of the necessary. boric anhydride (B 0 can be .supplied as. borax, whereas withnormal; sodium zirconium silicate, practically auahe, B was supplied as boric acid whichv compound .an expensivesource of. B 0 .Hence a marked saving in glass costs is secured by utilizinginy new product whereinless than the theoretical quantity of sodium carbonate required to form a normal sodium zirconium silicate is used .inpreparingthe improved zirconium opaci'fying product.

and sodium carbonatetabout' 22 parts by weight, to about 900950 (3., and cooling and disintegrating the resulting mass.

,bonate has combined with the zirconium silicate.

4. A zirconium opacifier for Vitreous enameling glasses smelted at temperatures be-I low 1100 0. consisting of a roasted product containing normal sodium zirconiumsilicate approximately and undecomposed zirconium silicate'about 45%. p c

5. A zirconium opacifier consisting of a roasted product containing approximately by analysis the following constituents: zirconium oxide, 55%; silica 28%; sodium oxide, 14%, with traces of'oxides of-Yiron,

titanium, aluminumand phosphorus; also traces of carbon dioxide and water. CHARLES J. KINZIE; 

